Sedimentological and micropalaeontological evidence to elucidate post-evaporitic carbonate palaeoenvironments of the Saudi Arabian latest Jurassic
Journal Title: Volumina Jurassica - Year 2008, Vol 6, Issue 1
Abstract
The Hith Formation forms the youngest lithostratigraphic unit of the Jurassic Shaqra Group. It represents the culmination of a succession of hypersaline and euryhaline cycles that characterise the Late Jurassic of Saudi Arabia. The Formation is poorly exposed in central Saudi Arabia, but it has been studied in detail in subsurface eastern Saudi Arabia where the upper carbonate member hosts an important hydrocarbon reservoir called the Manifa Reservoir. Chronostratigraphic control is absent from the formation itself, and the Tithonian age is suggested for the Hith Formation based on its stratigraphic position between the underlying Arab Formation of Late Kimmeridgian age, and the overlying Sulaiy Formation, of Late Tithonian to Berriasian age.The Hith Formation needs redefining in the light of new lithological evidence, and a tripartite member scheme is suggested. This includes the lower anhydrite-dominated member here termed the “anhydrite” member, and considered to represent hypersaline subaqueous deposition within a restricted deep lagoon during the lowstand systems tract of the Manifa sequence. A “transitional“ member consists of interbedded anhydrites and carbonates and approximates with the transgressive zone. The overlying “carbonate” member represents the results of a prograding shallow, normal salinity marine succession related to the highstand systems tract. Interbedded carbonates within the evaporites are interpreted to represent superimposition of a higher frequency, possibly 4th order eustatic cyclicity.The “carbonate“ member hosts the Manifa Reservoir, and here proposed as the Manifa Member, consist of five parasequences, each of which represents a shoaling-upwards cycle with a succession of up to five repeated lithofacies and biofacies that commences with a stromatolitic, microfaunally-barren unit followed by fine-grained grainstones with a monospecific but abundant ostracod biofacies. A succession of coarse pelloidal grainstones with rare foraminifera, including [i]Redmondoides lugeoni[/i], [i]Trocholina alpina [/i]with a variety of unidifferentiated valvulinids and miliolids then follows, that passes vertically into coarse ooid grainstones, with rare [i]Redmondoides lugeoni[/i], forming the uppermost part of each parasequence.
Authors and Affiliations
Geraint HUGHES, Nassir NAJI
Keywords
Related Articles
- EP ID EP67911
- DOI -
- Views 69
- Downloads 0
7th International Congress on the Jurassic System, Kraków, Poland, September 6-18, 2006
COACHING – TREND OR REAL SUPORT IN ORGANIZATION MANAGEMENT AND UNIT DEVELOPMENT? BENEFITS AND THREATS
This work concerns a subject of coaching popularity nowadays and its benefits and threats. Attractiveness of coaching may cause that people without proper competences, ethics and responsibility about their work will want...
Sołtyków – unikalny zapis paleoekologiczny wczesnojurajskich utworów kontynentalnych
KOMPETENCJE INFORMATYCZNE – Z PERSPEKTYWY PRACOWNIKÓW
Opracowanie prezentuje wyniki pierwszego etapu badań prowadzonych w ramach re-alizacji projektu badawczego „Kompetencje informatyczne pracowników MŚP jako istotny element zapewnienia efektywnego, innowacyjnego i konkuren...
[b]A review of the Lower – lowermost Upper Jurassic facies and stratigraphy of the Jaisalmer Basin, western Rajasthan, India[/b]
The Lower – lowermost Upper Jurassic (up to Oxfordian) sedimentary succession of the Jaisalmer Basin on the Rajasthan Shelf is characterized by gradual lateral and rapid temporal facies variations, the existence of conde...